Importing html image with no source and then exporting it to pdf causes an exception, instead of omitting the faulty image.

Such images can be stripped using the following workaround:

List<ImageInline> images = this.document.EnumerateChildrenOfType<ImageInline>().ToList();

foreach (var image in images)
{
      if (image.Image.ImageSource == null)
      {
               image.Paragraph.Inlines.Remove(image);
      }
}

You can add captions to figures, equations, or other objects.

From the Office Open XML File Formats Specification: This element specifies the contents and positioning for captions which can be used to automatically label objects in a WordprocessingML document. A caption is a string that labels an object included in a WordprocessingML document, and typically consists of a string plus a field which numbers this item within a collection of similar objects.

Similar functionality can be achieved using the CustomCodeField:

RadFlowDocumentEditor editor = new RadFlowDocumentEditor(document);
using (Stream stream = File.OpenRead("Image1.jpg"))
{
	ImageInline image = editor.InsertImageInline(stream, "jpg");
	editor.InsertBookmark("Image", image, image);
}

editor.InsertBreak(BreakType.LineBreak);
editor.InsertText("Figure ");
editor.InsertField("SEQ Image", "Update Figure Number");

This feature includes: table of figure, table of tables etc.

TOC field contains PageRef fields inside it. To update it, we will need pagination (layout) support and PageRef fields implementation. Also TOC update can be influenced by TC fields presence in the document.

Implement export to PDF.

The non-breaking hyphen element is currently not supported in the model and is stripped when importing the document.

Introduce new section properties which are responsible for defining columns in the section.

Implement import of PDF to RadFlowDocument, using PdfFormatProvider. This would require text recognition (including determining where paragraphs end as opposed to new line inserted because of the layout) and table recognition.

This will allow conversion of PDF documents to docx, RTF and HTML.

The custom document properties enable the users to define their own properties to the document or use one of the predefined. 

In most of the cases, the document variables can be used instead. More information about them you can find at http://docs.telerik.com/devtools/document-processing/libraries/radwordsprocessing/concepts/fields/document-variables